Transitioning between wideband and narrowband communications

ABSTRACT

A wireless device sends, to an access point, an indication to the access point that the wireless device is to transition between a wideband communication and a narrowband communication.

BACKGROUND

Devices such as computers, handheld devices, or other types of devicescan communicate over wired or wireless networks. Wireless networks caninclude a wireless local area network (WLAN), which includes wirelessaccess points (APs) to which devices are able to wirelessly connect.Other types of wireless networks include cellular networks that includewireless access network nodes to which devices are able to wirelesslyconnect.

BRIEF DESCRIPTION OF THE DRAWINGS

Some implementations of the present disclosure are described withrespect to the following figures.

FIG. 1 is a block diagram of an example network arrangement according tosome implementations.

FIG. 2 is a flow diagram of an example process performed by a wirelessdevice according to some implementations.

FIG. 3 is a state diagram illustrating transitions between communicationmodes of a wireless device according to some implementations.

FIGS. 4-7 are flow diagrams illustrating transitions between widebandand narrowband communication modes, according to some implementations.

FIG. 8 is a flow diagram of discovering and associating with an accesspoint, followed by a transition from a wideband communication mode to anarrowband communication mode, according to further implementations.

FIG. 9 is a block diagram of a wireless node according to some examples.

DETAILED DESCRIPTION

In a wireless local area network (WLAN), a wireless device (which canalso be referred to as a client device) may communicate with one ormultiple wireless access points (APs). A wireless AP (or more simply, anAP) can refer to a communication device to which a wireless device canestablish a wireless connection to communicate with other endpointdevices. WLANs can include wireless networks that operate according tothe Institute of Electrical and Electronic Engineers (IEEE) 802.11specifications. In other examples, WLANs can operate according to otherprotocols. More generally, techniques or mechanisms according to someimplementations of the present disclosure can be used with other typesof wireless networks, such as cellular networks or other wirelessnetworks.

Examples of wireless devices include computers (e.g., tablet computers,notebook computers, desktop computers, etc.), handheld devices (e.g.,smart phones, personal digital assistants, etc.), wearable devices(smart watches, electronic eyeglasses, virtual reality headsets, etc.),game appliances, health monitors, vehicles (or equipment in vehicles),or other types of endpoint or user devices that are able to communicatewirelessly.

In some examples, the channel widths of a frequency channel used incommunications over a WLAN that operates according to the IEEE 802.11specifications can be 20 megahertz (MHz) or 40 MHz. A WLAN can employ 20MHz (or 40 MHz) channels in the 2.4 gigahertz (GHz) frequency band, insome examples. Although reference is made to specific example channelwidths and frequency bands, it is noted that in other examples,techniques or mechanisms according to some implementations can be usedwith other channel widths and frequency bands.

In the present disclosure, a WLAN that operates using 20 MHz or 40 MHzchannels (or frequency channels of other widths) can be referred to as awideband WLAN. Channels used by a wideband WLAN can be referred to aswideband channels.

The Long Range Low Power (LRLP) technology for WLAN communications hasbeen proposed for IEEE 802.11. LRLP is also known as Wake Up Radio (WUR)or IEEE 802.11ba or IEEE 802.11bb. LRLP uses frequency channel widthsthat are less than the channel width of a wideband WLAN. For example,LRLP can employ channel widths of approximately 2 MHz. In otherexamples, a narrowband channel can have a channel width of approximately1 MHz, 5 MHz, 10 MHz, or any other width that is less than the channelwidth of a wideband channel. A frequency channel that has a channelwidth less than that of the frequency channel used in a wideband WLANcan be referred to as a narrowband channel.

More generally, a narrowband WLAN can refer to a WLAN in whichcommunications between stations (STAs) or between a STA and an AP canemploy a frequency channel having a channel width (or frequency range)less than the channel width (or frequency range) of a channel used by awideband WLAN. According to IEEE 802.11, a STA is a device that has thecapability to use the 802.11 protocol. A STA can be an AP, oralternatively, a STA can be a non-AP STA, such as any of the wirelessdevices discussed above.

In some examples, a narrowband WLAN uses a narrowband channel that isphysically located within the wideband channel of a wideband WLAN. Inother words, the narrowband channel of the narrowband WLAN is a subsetof a wideband channel of a wideband WLAN. The narrowband channel canalso be considered to be a sub-channel of the wideband channel. In someexamples, the narrowband channel can be centered around the same centerfrequency as the wideband channel. In other examples, the narrowbandchannel does not have to be centered around the same center frequency asthe wideband channel. In yet further examples, the narrowband channelmay be an orthogonal frequency-division multiple access (OFDMA)allocation block.

Although reference is made to wideband WLANs and narrowband WLANs, it isnoted that techniques or mechanisms according to some implementationscan also be used with other types of wireless networks that can includewideband wireless networks and narrowband wireless networks, with awideband wireless network using a wideband channel and a narrowbandwireless network using a narrowband channel that is a subset of thewideband channel.

FIG. 1 shows an example WLAN 100 that includes an AP 102. Although justone AP is depicted in FIG. 1, it is noted that the WLAN 100 can includemultiple APs. If the wireless network 100 is a cellular access network,then the AP 102 can be considered a wireless access network node, suchas an eNodeB or a base station.

The AP 102 is able to serve both wireless devices communicating inwideband channels and wireless devices communicating in narrowbandchannels. The AP 102 includes a wideband interface 104 to communicatewith wireless devices over wideband channels, and a narrowband interface106 to communicate with wireless devices over narrowband channels. Thewideband interface 104 can include a physical layer (PHY) and a MediumAccess Control (MAC) layer (which is a layer 2 above the physicallayer). The MAC/PHY layers of the wideband interface 104 are configuredto communicate over the wideband channels. Similarly, the narrowbandinterface 106 includes a PHY and a MAC layer, which are configured tooperate in narrowband channels.

Several types of wireless devices are depicted in FIG. 1. A legacywireless device 108 includes a wideband interface 110 to communicateover wideband channels. The legacy wireless device 108 is a wirelessdevice that is able to operate in the wideband channels, but not in thenarrowband channels. The legacy wireless device 108 may also be capableof operating in other channels (e.g., using other non-WLAN interfaces).

A narrowband wireless device 112 includes a narrowband interface 114 tocommunicate with the AP 102 over narrowband channels. A narrowbandwireless device 112 is not able to communicate over wideband channels.The narrowband wireless device 112 may also be capable of operating inother channels (e.g., using other non-WLAN interfaces).

A dual-capable wireless device 116 includes both a wideband interface118 and a narrowband interface 120. The dual-capable wireless device 116is able to communicate over either wideband channels or narrowbandchannels. The dual-capable wireless device 116 may also be capable ofoperating in other channels (e.g., using other non-WLAN interfaces).

The dual-capable wireless device 116 is able to selectively operate ineither a wideband communication mode or a narrowband communication mode.In the wideband communication mode, the wireless device 116 communicateswith the AP 102 using a wideband channel, while in the narrowbandcommunication mode, the wireless device communicates with the AP 102using a narrowband channel. In some examples, a time-based sharing of afull channel is performed between narrowband and wideband communicationmodes; in other words, the AP 102 communicates with wireless devices innarrowband channels at designated (e.g., scheduled or predefined) timeintervals, while in other time intervals, the AP 102 communicates withwireless devices using wideband channels.

A dual-capable wireless device (e.g., 116) that is capable of bothnarrowband and wideband communication modes can be viewed in one of twodifferent ways. In some examples, the wireless device can be a low powerwireless device that has additional wideband communication capabilitiesused to speed up or otherwise enhance system acquisition and improvedata transfer rates. In other examples, the wireless device is a regularWLAN wireless device that has additional narrowband capabilities toenhance power savings or to increase communication range. When an STA(either a wireless device or an AP) operates in the narrowbandcommunication mode, power savings can be achieved due to lower powerconsumption associated with communications over a narrowband channel,and because the narrowband interface can use a low duty cycle (e.g., anarrowband transceiver of the STA is turned off for a longer period oftime as compared to a wideband transceiver).

Various issues can arise relating to operations in a WLAN (or otherwireless network) in which wireless devices and APs are able to operatein multiple communication modes, including the wideband communicationmode and the narrowband communication mode.

Issue 1

Issue 1 relates generally to how the AP can be made aware of a currentcommunication mode (wideband communication mode or narrowbandcommunication mode) of a wireless device. Current IEEE 802.11 LRLPdesigns specify an AP serving either wideband or narrowband wirelessdevices, and do not specifically address the case of an AP that is ableto serve a wireless device (such as the dual-capable wireless device 116of FIG. 1) that is able to operate in both the wideband and narrowbandcommunication modes. The AP has to know what communication mode(wideband communication mode or narrowband communication mode) thedual-capable wireless device is in at all times so that the AP cantransmit to the dual-capable wireless device using a correct channel(either a wideband channel or narrowband channel). In some examples, ifthe dual-capable wireless device chooses to transition from thenarrowband communication mode to the wideband communication mode in themiddle of a long paging or sleep cycle (during which the transceiver ofthe wireless device is powered off), the AP may lose connectivity withthe wireless device. Even if connectivity is not lost, the AP has toknow which communication mode the wireless device is using, so that theAP can transmit information to the wireless device using the appropriatechannel (wideband channel or narrowband channel). The AP also has tohandle the situation in which downlink data packets are queued when awireless device operating in narrowband communication mode issleeping—such downlink data packets have to be delivered immediatelyafter a client-initiated transition to the wideband communication mode.

Issue 2

Issue 2 relates to the length of time associated with discovering anarrowband WLAN by a wireless device. A wireless device, such as thedual-capable wireless device 116, is able to perform scanning for bothnarrowband and wideband WLANs. Scanning can include passive scanning,where the wireless device can tune the wireless device's receiver to aparticular channel (either the narrowband channel or wideband channel).In passive scanning, the wireless device decodes received frames from anAP to look for a Beacon frame. A “frame” refers to a unit of informationthat can be communicated wirelessly between a wireless device and aWLAN. A Beacon frame is periodically sent by an AP, and containsinformation to allow a wireless device to discover a WLAN.

Alternatively, scanning can include active scanning, in which a wirelessdevice sends, to an AP, a Probe request, and waits for a Probe responsefrom the AP. Passive scanning or active scanning can take a relativelylong period of time, especially to discover a narrowband WLAN. Theamount of time that is involved in detecting a narrowband WLAN can bemultiplied by the number of available narrowband channels. If there aremultiple narrowband channels, then a wireless device may have to scaneach of the narrowband channels. Spending a relatively long period oftime scanning for a WLAN can consume battery power of the wirelessdevice, and can lead to delays in communications.

1. Solutions Relating to Transitioning Between Narrowband and WidebandCommunication Modes

The following describes example solutions that can be used to addressIssue 1 discussed above.

FIG. 2 is a flow diagram of an example process that can be performed bya wireless device, such as the wireless device 116, according to someimplementations. The wireless device decides (at 202) to transitionbetween the wideband communication mode and the narrowband communicationmode. Thus, in some examples, the wireless device can decide totransition from the narrowband communication mode to the widebandcommunication mode, while in other examples, the wireless device candecide to transition from the wideband communication mode to thenarrowband communication mode. The decision to transition between thewideband communication mode and the narrowband communication mode can bebased on various factors, such as one or more of the following: enter alower power mode (the narrowband communication mode) to reduce powerconsumption at the wireless device, increase a communication range ofthe wireless device by entering the narrowband communication mode, enterthe wideband communication mode to achieve higher data communicationrates, and so forth.

In response to the decision to transition between the widebandcommunication mode and the narrowband communication mode, the wirelessdevice sends (at 204) an indication to the AP (e.g., the AP 102 ofFIG. 1) that the wireless device is to transition between the widebandcommunication mode and the narrowband communication mode.

The indication sent to the AP can be an indication that the wirelessdevice is to transition from the wideband communication mode to thenarrowband communication mode, or from the narrowband communication modeto the wideband communication mode. By sending the indication, the AP isable to determine the communication mode to use to communicate with thewireless device, so that the AP is able to send data to the wirelessdevice using the appropriate one of a wideband channel or a narrowbandchannel.

FIG. 3 is a state diagram that illustrates transitions between thewideband communication mode 302 and the narrowband communication mode304 by a wireless device that is able to perform both wideband andnarrowband communications. In some examples, the wideband communicationmode 302 has an awake state 306 and a doze state 308. The awake state306 is an active state of the wireless device when in the widebandcommunication mode 302. The doze state 308 is a power savings state inwhich certain components of the wireless device, such as the wirelessdevice's transmitter and/or receiver, have been powered off.

The narrowband communication mode 304 is considered a power save statewhen compared to the awake state 306 of the wideband communication mode302. Although not shown in FIG. 3, the narrowband communication mode 304may have one or more sub-states that operate at respective differentpower levels.

In some examples, the operation of the narrowband communication mode 304differs from the operation of the doze state 308 of the widebandcommunication mode 302 in some aspects. When a wireless devicetransitions to the doze state 308, the wireless device sends a messageto an AP informing the AP that the wireless device has entered the dozestate 308. From that point on, the AP does not immediately send dataframes to the wireless device, but instead queues the data frames. TheAP can send an indication (such as a flag in a Downlink TrafficIndication Map or DTIM that is part of a Beacon frame) to the wirelessdevice that there is data pending. The wireless device in the doze state308 can periodically power on its receiver to receive and decode theindication (such as the DTIM in the Beacon frame). In response to theindication that there is data pending for the wireless device, thewireless device can transition from the doze state 308 to the awakestate 306 to receive the data from the AP.

In contrast, in the narrowband communication mode 304, the wirelessdevice does not have to monitor Beacon frames sent on a widebandchannel.

In some implementations, transitions between the wideband communicationmode 302 and the narrowband communication mode 304 can involve use offour different types of indications (sent at 204 in FIG. 2):

(1) an indication to transition from the wideband communication mode 302to the narrowband communication mode 304,

(2) an indication to transition from the narrowband communication mode304 to the wideband communication mode 302,

(3) a direct transition from the narrowband communication mode 304 tothe wideband communication mode 302, and

(4) a direct transition from the wideband communication mode 302 to thenarrowband communication mode 304.

The use of these four different types of indications are discussedfurther below in sections 1.1, 1.2, 1.3, and 1.4.

In some examples, a narrowband and wideband WLAN operates as a singlebasic service set (BSS) from the perspectives of usage of a MAC addressand an association state between a client STA (non-AP STAs) and an AP. ABSS refers to a network that includes a single AP and one or more clientSTAs associated with the AP.

As the wideband and narrowband PHYs of a STA (either a client STA or anAP) operate as a single BSS, once a client STA associates with the AP,the same association between the client STA and the AP is maintained(and does not change) in response to transitions between the widebandand narrowband communication modes. In this case, the same associationcan apply to authentication and mobility parameters, or justauthentication parameters.

The AP can maintain communication mode information (or more generally,status information) for all client STAs that are associated with the AP.The communication mode information maintained by the AP for a givenclient STA can indicate to the AP whether the given STA is operating inthe wideband communication mode or the narrowband communication mode. Insome examples, the storage of the communication mode information may bebased on the MAC address of the given client STA, where the MAC addressis a global identifier of the client STA. Thus, based on a specific MACaddress that corresponds to a respective client STA, the AP is able toretrieve the corresponding communication mode information to determinethe communication mode currently used by the respective STA. In otherexamples, the communication mode information can be associated with anassociation identifier (AID), which is a local address assigned to eachclient STA by the AP (e.g., a number between 1 and 2007).

In some examples, a client STA operating in a first communication mode(wideband communication mode or narrowband communication mode) can sendan indication on the current communication interface (widebandcommunication interface or narrowband communication interface) to set upthe transition to a second, different communication mode (narrowbandcommunication mode or wideband communication mode). Such operations aredescribed below in sections 1.1 and 1.2.

In other examples, the client STA operating in a first communicationmode (wideband communication mode or narrowband communication mode) canimmediately transmit on the other communication interface (narrowbandcommunication interface or wideband communication interface), where thetransmission on the other communication interface provides an indicationof a transition between the wideband communication mode and narrowbandcommunication mode. Such operations are described below in sections 1.3and 1.4.

Although communication mode transitions are described as being initiatedby a client STA (or another client device), it is noted that in otherexamples, an AP can trigger a client STA (or another client device) toperform the communication mode transition.

In some examples, if a client STA is currently in the widebandcommunication mode, the regular WLAN (active state or doze state)procedure for delivering downlink frames from the AP to the client STAcan be used, where the downlink frames are queued or transmitted to theclient STA as appropriate according to the IEEE 802.11 specifications.If the STA is currently in the narrowband communication mode, anydownlink frames can be queued until the time when the AP is operating inthe narrowband communication mode, at which time the downlink frames canbe transmitted to the client STA.

1.1. Indication of Transitioning from the Wideband Communication Mode tothe Narrowband Communication Mode

This section describes examples where the indication that is sent (at204) in FIG. 2 by the wireless device to an AP is an explicit indicationto transition from the wideband communication mode to the narrowbandcommunication mode.

As shown in FIG. 4, the indication is in the form of a narrowbandtransition request sent (at 402) by the wireless device 116 to the AP102. The sending of the narrowband transition request can be initiatedby the wireless device 116, or alternatively, can be triggered by the AP102 sending a trigger message (not shown) to the wireless device 116.The wireless device 116 can accept or reject the trigger message, and inthe case that the wireless device 116 rejects the trigger message, thewireless device 116 can send a reason code, such as a reason codespecified in Section 9.4.1.7 of IEEE 802.11-REVmc/D6.0, or anotherreason code. The reason code is also known as a status code.

The narrowband transition request is sent from the wireless device 116to the AP 102 over a wideband network (using a wideband channel) toinform the AP 102 of the wireless device's intended transition from thewideband communication mode to the narrowband communication mode.

The AP 102 responds to the narrowband transition request by sending (at404) to the wireless device 116 a narrowband transition response overthe wideband network. The AP 102 may accept or reject the narrowbandtransition request, and can indicate the acceptance or rejection in thenarrowband transition response.

Assuming that the AP 102 accepts the narrowband transition request, theAP 102 can begin queuing downlink frames for the wireless device 116after transmitting the narrowband transition response, such that thequeued downlink frames will be delivered using the narrowband networkaccording to whichever power saving scheme is being used by the wirelessdevice 116 on the narrowband network.

In response to the narrowband transition response (and assuming thenarrowband transition response contains an acceptance indication thataccepts the narrowband transition request), the wireless device 116sends (at 406) a narrowband transition confirm to the AP 102 over anarrowband network (using a narrowband channel), to indicate asuccessful transition to the narrowband communication mode.

The narrowband transition confirm is sent on the narrowband network toindicate a successful transition by the wireless device 116 to thenarrowband communication mode. In some cases, there can be delay betweenthe narrowband transition response and the narrowband transitionconfirm, because the wireless device 116 may have to wait to transmitthe narrowband transition confirm until the AP 102 is operating in thenarrowband communication mode.

In response to the narrowband transition confirm, the AP 102 updates (at408) the communication mode information for the wireless device 116, toindicate that the wireless device 116 is now operating in the narrowbandcommunication mode. In some examples, the communication mode informationcan be stored in a communication mode information table (or other datastructure), where different entries of the communication modeinformation table can store communication mode information for differentwireless devices.

In some examples, the narrowband transition request can include a reasoncode that can indicate a reason for the request to transition from thewideband communication mode to the narrowband communication mode. Thereason code can include information in an information element of thenarrowband transition request. The reason code in the narrowbandtransition request can specify any of the following reasons forrequesting the transition to the narrowband communication mode: reducingpower, low battery, low signal-to-noise ratio, reducing requiredbandwidth, etc. The narrowband transition request can also include arequested sleep cycle length (the amount of time that the no datatransmission is occurring) and other parameters of the low-powernarrowband communication mode.

The narrowband transition response can include information aboutoperation of the narrowband network (and how the wireless device shouldaccess the narrowband network) such as any or some combination of thefollowing: narrowband transmit period duration, narrowband transmitperiod cycle duration, channel width, which particular sub-channel(i.e., which of the narrowband channels within a wideband channel) tooperate on, etc. In examples where some of the foregoing informationrelating to narrowband communication is dynamic, the narrowbandtransition response can include the most up-to-date values of theinformation at the time of the transition to the narrowbandcommunication mode.

If the AP 102 rejects the narrowband transition request, then thenarrowband transition response includes an indication of the rejectionof the narrowband transition request, and a reason code for therejection. Reason codes such as those specified in Section 9.4.1.7 ofIEEE 802.11-REVmc/D6.0 can be used. In further examples, additionalreason codes can be used in the narrowband transition response. Therecan be two categories of reason codes: a first category of reason codesthat allows for future narrowband transition request from the wirelessdevice 116, and a second category of reason codes that bars futurenarrowband transition requests.

Subsequent to sending the confirm message the wireless device 116continues to perform subsequent narrowband communications (at 410) withthe AP 102 in the narrowband communication mode until a transition tothe wideband communication mode is performed.

In some examples, the format of a narrowband transition request can beas follows:

Narrowband Narrowband Element ID Length Features Parameters Octets: 1 12 variable

The wireless device can set the Narrowband Features field of thenarrowband transition request to a value indicating which features ofthe narrowband communication mode are being requested. The features caninclude Low Power, Ultra Low Power, Long Range, etc. For example, likethe wideband network, the narrowband network may have different levelsof power save features that are available for use.

The wireless device can set the Narrowband Parameters field of thenarrowband transition request to indicate PHY and MAC features, such asreceive/transmit (Rx/Tx) power levels, forward error correction (FEC),encoding, modulation, window size, preamble, etc. The features includedin the Narrowband Parameters field may be the full list the wirelessdevice is capable of supporting, or the features included in theNarrowband Parameters field may be a subset of the supportedcapabilities that the wireless device intends to use at this time.

In some examples, the format of a narrowband transition response can beas follows:

Ele- ment Status Narrowband Narrowband ID Length Code Schedule LengthParameters Octets: 1 1 1 variable 1 variable

The Status Code field of the narrowband transition response contains afirst value (e.g., 0) if the transition is accepted. If the transitionis rejected, the Status Code field contains a value that describes thereason for failure to transition, such as reason codes described insection 9.4.1.7 of IEEE 802.11-REVmc/D6.0.

The Narrowband Schedule field of the narrowband transition responsecontains the parameters of a power save sleep cycle in the narrowbandnetwork.

The AP sets the Narrowband Parameters field to indicate PHY and MACfeatures, such as Rx/Tx power levels, FEC, encoding, modulation, windowsize, preamble, etc. The AP can send a subset of the parameters thatwere in the request from the wireless device. The AP does not sendparameters the wireless device does not support. If the AP cannotsupport the parameters indicated in the narrowband transition requestfrom the wireless device, the AP should send one of the failure reasonsas the Status Code.

In some examples, the format of a narrowband transition confirm can beas follows:

Element ID Length Confirmation Octets: 1 1 1

The Confirmation field of the narrowband transition confirm contains aflag to indicate that the wireless device has successfully transitionedto the narrowband communication mode.

1.2 Indication of Transitioning from the Narrowband Communication Modeto the Wideband Communication Mode

This section describes examples where the indication that is sent (at204) in FIG. 2 by the wireless device to an AP is an explicit indicationto transition from the narrowband communication mode to the widebandcommunication mode.

As shown in FIG. 5, the indication is in the form of a widebandtransition request sent (at 502) by the wireless device 116 to the AP102. The sending of the wideband transition request can be initiated bythe wireless device 116, or alternatively, can be triggered by the AP102 sending a trigger message (not shown) to the wireless device 116.The wideband transition request can contain a reason code.

The wideband transition request is sent from the wireless device 116 tothe AP 102 over a narrowband network (using a narrowband channel) toinform the AP 102 of the wireless device's planned transition from thenarrowband communication mode to the wideband communication mode.

The AP 102 responds to the wideband transition request by sending (at504) to the wireless device 116 a wideband transition response over thenarrowband network. The AP 102 may accept or reject the widebandtransition request, and can indicate the acceptance or rejection in thewideband transition response using a reason code. One of the reasons theAP may reject the wideband transition request is because of lack ofresources to serve the STA in that mode. This is a form of admissioncontrol to limit the number of devices simultaneously using the widebandchannel.

In response to the wideband transition response (and assuming thewideband transition response contains an acceptance indication thataccepts the wideband transition request), the wireless device 116 canmove over to the wideband channel and start performing subsequentwideband communications (at 508) over the wideband network immediately,or alternatively, can send (at 506) a wideband transition confirm overthe wideband network followed by performing subsequent widebandcommunications (at 508) on the wideband network.

In response to the wideband transition confirm (506) or receipt offrames over the wideband network (508), the AP 102 updates (at 507) thecommunication mode information for the wireless device 116, to indicatethat the wireless device 116 is now operating in the widebandcommunication mode.

In some examples, the formats of the wideband transition request,wideband transition response, and wideband transition confirm can besimilar to the formats of the narrowband transition request, narrowbandtransition response, and narrowband transition confirm discussed insection 1.1 above.

1.3 Direct Transition from the Narrowband Communication Mode to theWideband Communication Mode

This section describes examples where the indication that is sent (at204) in FIG. 2 by the wireless device to an AP is a frame that providesan indication to transition from the narrowband communication mode tothe wideband communication mode.

As shown in FIG. 6, the wireless device 116 is assumed to be operatingin the narrowband communication mode and performs narrowbandcommunications (at 602) with the AP 102 over the narrowband network. Thewireless device 116 that is currently in the narrowband communicationmode may send (at 604) an initial wideband frame to the AP 102 on awideband channel at any time while the AP 102 is operating in thewideband communication mode. Based on the communication mode informationmaintained for the wireless device 116 by the AP 102, the AP 102 thatreceives the initial uplink wideband frame is aware that the wirelessdevice 116 is currently in the narrowband communication mode. As aresult, receipt of the initial wideband frame is an indication of atransition from the narrowband communication mode to the widebandcommunication mode.

In response to the receipt of the initial uplink wideband frame (at604), the AP 102 updates (at 606) the communication mode information forthe wireless device 116, to indicate that the wireless device 116 is nowoperating in the wideband communication mode. Subsequent communicationsbetween the wireless device 116 and the AP 106 include subsequentwideband communications (at 608) over the wideband network, until thewireless device 116 initiates a transition back to the narrowbandcommunication mode.

As noted above, the AP 102 uses the same MAC address for the wirelessdevice 116 on each of the wideband and narrowband networks. As a result,the AP 102 has to determine the channel (narrowband or wideband channel)over which a given frame is transmitted by the wireless device 116. Thisdetermination can be based on a PHY header included in the given frame.The PHY header can include information indicating which of thenarrowband channel or wideband channel is used to transmit the givenpacket. The information in the PHY header indicating which of thenarrowband channel or wideband channel is used to transmit the givenpacket can be passed to a MAC layer in the AP 102.

In further examples, in response to the AP 102 receiving a frame on thewideband channel from the wireless device 116 that is currentlyoperating in the narrowband communication mode, the AP 102 can either(1) change the mode communication information for the wireless device116 to indicate that the wireless device 116 has transitioned to thewideband communication mode such that any subsequent frames arecommunicated over the wideband channel, or (2) determine that the use ofthe wideband channel is for one frame (or some other predeterminednumber of frames) only. For example, a frame can include a flag (orother information) in the header of the frame, where the flag issettable to multiple values. A first value of the flag indicates thatthe wireless device 116 intends to return to the narrowbandcommunication mode after a transmission of a single frame (or apredetermined number of frames) over the wideband channel.

A second value of the flag indicates that the wireless device 116intends to change to the wideband communication mode for subsequentcommunications of frames (i.e., the wireless device 116 is transitioningto the wideband communication mode such that the wireless device 116will continue to perform the subsequent communications in the widebandcommunication mode).

In some examples, the flag (or other information) may be encoded in aquality of service (QoS) Control Field or similar frame header. Thisinformation may be added to a data frame, or alternatively, may be addedto management frames such as a Null data frame or QoS Null data frame orPS-Poll frame to indicate the wireless device's mode change intention.

If the AP 102 has any downlink frames queued for wireless device 116while the wireless device 116 was in the narrowband communication mode,the initial wideband frame (sent at 604) may trigger the AP 102 todeliver the queued downlink frames on the wideband channel.

1.4 Direct Transition from the Wideband Communication Mode to theNarrowband Communication Mode

This section describes examples where the indication that is sent (at204) in FIG. 2 by the wireless device to an AP is an implicit indicationto transition from the wideband communication mode to the narrowbandcommunication mode.

As shown in FIG. 7, the wireless device 116 is assumed to be operatingin the wideband communication mode and performs wideband communications(at 702) with the AP 102 over the wideband network. The wireless device116 that is currently in the wideband communication mode may send (at704) an initial uplink narrowband frame to the AP 102 on a narrowbandchannel at any time while the AP 102 is operating in the narrowbandcommunication mode. The wireless device 116 has to be able to receivedownlink frames on the wideband channel up until the initial narrowbanduplink frame is transmitted.

Note that in some examples the AP 102 may be configured to receive anddecode narrowband frames at any time (even though this is resourceintensive). In other examples the AP 102 may be configured to receiveand decode narrowband frames at specific time intervals (and not toreceive and decode narrowband frames at other time intervals differentfrom the specific time intervals). In the latter examples, the wirelessdevice 116 only transmits the initial uplink narrowband frame at one ofthe specific time intervals for narrowband operation.

Based on the communication mode information maintained for the wirelessdevice 116 by the AP 102, the AP 102 that receives the initial uplinknarrowband frame is aware that the wireless device 116 is currently inthe wideband communication mode. As a result, receipt of the initialuplink narrowband frame is an implicit indication of a transition fromthe wideband communication mode to the narrowband communication mode.

In response to the receipt of the initial uplink wideband frame (at704), the AP 102 updates (at 706) the communication mode information forthe wireless device 116, to indicate that the wireless device 116 is nowoperating in the narrowband communication mode. Subsequentcommunications between the wireless device 116 and the AP 106 includesubsequent narrowband communications (at 708) over the narrowbandnetwork, until the wireless device 116 initiates a transition back tothe narrowband communication mode.

In further examples, in response to the AP 102 receiving a frame on thenarrowband channel from the wireless device 116 that is currentlyoperating in the wideband communication mode, the AP 102 can either (1)change the mode communication information for the wireless device 116 toindicate that the wireless device 116 has transitioned to the narrowbandcommunication mode such that any subsequent frames are communicated overthe narrowband channel, or (2) determine that the use of the narrowbandchannel is for one frame (or some other predetermined number of frames)only. For example, a frame can include a flag (or other information) inthe header of the frame, where the flag is settable to multiple values.A first value of the flag indicates that the wireless device 116 intendsto return to the wideband communication mode after a transmission of asingle frame (or a predetermined number of frames) over the narrowbandchannel. A second value of the flag indicates that the wireless device116 intends to change to the narrowband communication mode forsubsequent communications of frames (i.e., the wireless device 116 istransitioning to the narrowband communication mode such that thewireless device 116 will continue to perform the subsequentcommunications in the narrowband communication mode).

The flag or other information in the frame can be implemented in amanner similar to that described in section 1.3 above.

1.5 Rate Sets and State

When the wireless device associates with an AP, a set of supported ratesis exchanged. A “rate” can refer to a rate of communicating data betweenthe wireless device and the AP. A rate can also correspond to aModulation and Coding Scheme (MCS). The AP provides the wireless devicewith a set of supported rates (that are supported by the AP), includingthe following, as examples: high throughput (HT) rates, very highthroughput (VHT) rates, high efficiency (HE) rates, and low powernarrowband rates. Similarly, the wireless device provides the AP with aset of supported rates (that are supported by the wireless device),including the foregoing rates.

In some implementations of the present disclosure, the widebandcommunication mode and the narrowband communication mode can beimplemented using respective distinct subsets of rates of a full set ofrates. These subsets of rates are referred to as a wideband rate set(for the wideband communication mode) and a narrowband rate set (for thenarrowband communication mode) in the ensuing discussion. The full setof rates are all of the rates that are mutually supported by thewireless device and the AP, while a subset of the full set of ratesincludes just a portion of the full set of rates. Although reference ismade to one wideband rate set and one narrowband rate set in the presentdiscussion, it is noted that there can be multiple wideband rate setsand/or multiple narrowband rate sets in other examples.

Based on the exchange of supported rates between the wireless device andthe AP, each of the wireless device and AP can determine the supportedrates for the wideband rate set and the narrowband rate set, and each ofthe wireless device and AP can store the wideband rate set and thenarrowband rate set. More generally, the wireless device can receive,from the AP, a first rate set including one or more supported rates forcommunication over a wideband channel, and a second rate set includingone or more supported rates for communication over a narrowband channel.Similarly, the AP can receive, from the wireless device, a first rateset including one or more supported rates for communication over awideband channel, and a second rate set including one or more supportedrates for communication over a narrowband channel.

Signaling can be exchanged between the wireless device and the AP toswitch between the wideband and narrowband rate sets. This signaling isan alternative to the pre-transition indication described in sections1.1 and 1.2 used for triggering a transition between the widebandcommunication mode and the narrowband communication mode. In someexamples, a transition between the wideband communication mode and thenarrowband communication mode can be implemented as a change in the rateset used (i.e., a change between the wideband and narrowband rate sets),since the rate set used indicates the communication mode.

The AP can control the transition of the wireless device between thewideband communication mode and the narrowband communication mode byimplementing a change in the currently supported rate set that isexchanged with the wireless device at the time of association betweenthe wireless device and the AP. For example, when the wireless device isin the wideband communication mode, the currently used rate set is asubset of the full set of rates, where the subset can include just theHT and VHT rates. When the wireless device is in the narrowbandcommunication mode, the currently used rate set is a different subset ofthe full set of rates, where the different subset can include just thenarrowband rates.

In some examples, the signaling that can be used to trigger a change inrate sets can include a Traffic Specification (TSPEC) message or a BlockACK message transmitted between the wireless device and the AP.Typically, the full rate set would be exchanged at the time ofassociation between the wireless device and the AP. The foregoingsignaling can be used to switch between two (or more) distinct subsetsof the full rate set. Alternatively, the full rate set or subset ofrates may be exchanged in the foregoing signaling when changingcommunication modes.

An explicit division of the full rate set can be performed atassociation time to group the rates of the full rate set into thewideband rate set and the narrowband rate set. Alternatively, thewideband rate set and the narrowband rate set can be implicitly based ona definition of the narrowband rate set being distinct from other ratesets.

For example, the narrowband rate set can be specified in an additionentry of a MAC layer management entity (MLME) Join Request, or an MLMEStart Request, where the MLME Join Request and MLME Start Request areexplained in IEEE 802.11-2016. In other examples, the narrowband rateset can be specified in a different message. The MLME is a managemententity that provides management service interfaces through which layermanagement functions may be invoked for the MAC layer. The Join Requestand the Start Request are used as part of the management functions forthe MAC layer.

As noted above, TSPEC messages can be used as signaling to trigger achange between a wideband rate set and a narrowband rate set. Forexample, TSPEC Add Traffic Stream (ADDTS) request and response messagescan be used. ADDTS is described in IEEE 802.11-2012. The ADDTS requestand response messages can be used to negotiate adding and removing oftraffic streams (TS). The primitives used for the foregoing are referredto as TS Management primitives, which include MLME-ADDTS.yyy andMLME-DELTS.yyy primitives, where yyy denotes request, confirm,indication, or response. An additional entry can be included in theMLME-ADDTS.indication( ) confirm( ) or response( ) primitive, where theadditional entry can include an indication for controlling selection ofa subset of rates (selection between the wideband rate set andnarrowband rate set). Note that there can be multiple wideband ratesets, referred to as OperationalRateSet and HTOperationalRateSet, wherethe HTOperationalRateSet includes rates that are HT rates not includedin the OperationalRateSet.

In further examples noted above, Block ACK messages can be used assignaling to trigger a change between a wideband rate set and anarrowband rate set. Similar to the TSPEC negotiation, the rate set canbe changed during the Block ACK agreement procedure. A first indicator(e.g., a bit or flag) in a Block ACK message is defined to indicatesupport of the multiple operational rate sets (wideband and narrowbandrate sets). A second indicator in the Block ACK message is used toswitch between the multiple rate sets. For example, a first value of thesecond indicator indicates use of a wideband rate set, while a second,different value of the second indicator indicates use of a narrowbandrate set. Alternatively, the second indicator can indicate a statechange where a first value indicates use of a current rate set, and asecond value indicates a change of rate set.

2. Discovering a Narrowband Network

The following describes examples of how the communication modetransition of section 1 can be used as part of a network discoveryprocess for a wireless device (e.g., the wireless device 116) thattypically operates in the narrowband channel.

The process of the wireless device 116 connecting to the network isshown in FIG. 8. It involves three main stages: (1) discovery andassociation performed in the wideband channel, (2) a communication modetransition from operating in the wideband channel to the narrowbandchannel, and (3) continued operation in the narrowband channel.

As shown in FIG. 8, discovery and association 802 performed between thewireless device 116 and AP 102 includes scanning (at 804), by thewireless device 116, the wideband channels, such as according to IEEE802.11, where the scanning can include active scanning or passivescanning. The scanning identifies one or more APs. The discovery andassociation 802 further includes performing association andauthentication 806, where the association and authentication 806includes the following tasks:

-   -   806.1) For each AP detected, the wireless device 116 determines        if the AP is narrowband capable—the wireless device 116 can make        this determination based on a capability bit in the beacon or        probe response, or an Access Network Query Protocol (ANQP)        response.    -   806.2) The wireless device 116 selects, from among the detected        APs, an AP to associate with, using the narrowband capabilities        of the APs as a factor in the selection. For example, the        wireless device 116 excludes from consideration any detected AP        that does not support narrowband communications, such that the        wireless device 116 would not select the AP without narrowband        support.    -   806.3) The wireless device 116 connects to the selected AP using        a regular wideband association procedure, such as according to        IEEE 802.11.    -   806.4) The wireless device 116 receives information or        parameters for the operation in the narrowband communication        mode.

The wireless device 116 then performs a mode transition (808), whichincludes informing the AP of the communication mode change from thewideband communication mode to the narrowband communication mode. Forexample, using the indication technique of section 1.1 above, thewireless device 116 sends (at 810), to the AP 102, a narrowbandtransition request, receives (at 812), from the AP 102, a narrowbandtransition response, and sends (at 814), to the AP 102, a narrowbandtransition confirm.

The wireless device 116 and the AP 102 can then perform subsequentnarrowband communications (at 816).

In alternative examples, the narrowband capability may not be advertisedby APs or may not be available prior to association. If this is thecase, then tasks 804 and 806.1-806.3 follow traditional WLAN procedures,while tasks 806.4 and 810-816 follow the procedures described in thepresent disclosure.

In further examples, the wireless device 116 receives sufficientinformation in task 806.1 such that task 806.4 or task 808 does not haveto be performed.

For a wireless device that is specifically designed as a low powerdevice (for operation in the narrowband communication mode), thewideband communication mode may only be used for associating to the AP.For this type of wireless device, following association with the AP inthe wideband communication mode, the wireless device will immediatelytransition to the narrowband communication mode and remain operating inthat mode for the rest of the association to the AP.

3. System Architecture

FIG. 9 is a block diagram of a wireless node 900, which can be awireless device (e.g., a non-AP STA) or an AP. The wireless node 900includes a processor (or multiple processors) 902, which can be coupledto one or more communication interface(s) 904 to communicate over awireless link, and to a non-transitory machine-readable orcomputer-readable storage medium 906 storing machine-readableinstructions 908 executable on the processor(s) 902 to perform varioustasks as described above.

A processor can include a microprocessor, a core of a multi-coremicroprocessor, a microcontroller, a programmable integrated circuit, aprogrammable gate array, or another hardware processing circuit.

The storage medium 906 can include one or multiple different forms ofmemory including semiconductor memory devices such as dynamic or staticrandom access memories (DRAMs or SRAMs), erasable and programmableread-only memories (EPROMs), electrically erasable and programmableread-only memories (EEPROMs) and flash memories; magnetic disks such asfixed, floppy and removable disks; other magnetic media including tape;optical media such as compact disks (CDs) or digital video disks (DVDs);or other types of storage devices. Note that the instructions discussedabove can be provided on one computer-readable or machine-readablestorage medium, or can be provided on multiple computer-readable ormachine-readable storage media distributed in a large system havingpossibly plural nodes. Such computer-readable or machine-readablestorage medium or media is (are) considered to be part of an article (orarticle of manufacture). An article or article of manufacture can referto any manufactured single component or multiple components. The storagemedium or media can be located either in the machine running themachine-readable instructions, or located at a remote site from whichmachine-readable instructions can be downloaded over a network forexecution.

In the foregoing description, numerous details are set forth to providean understanding of the subject disclosed herein. However,implementations may be practiced without some of these details. Otherimplementations may include modifications and variations from thedetails discussed above. It is intended that the appended claims coversuch modifications and variations.

What is claimed is:
 1. An access point comprising: communicationinterfaces to communicate over a wideband channel and a narrowbandchannel; at least one processor configured to: receive, from a wirelessdevice, an indication that the wireless device is to transition betweena wideband communication and a narrowband communication; and send, tothe wireless device, a first rate set including a plurality of supportedrates for communication between the access point and the wireless deviceover the wideband channel, and a second rate set including a pluralityof supported rates for communication between the access point and thewireless device over the narrowband channel, the first rate setincluding a supported rate not included in the second rate set.
 2. Theaccess point of claim 1, wherein the indication comprises an uplinkframe from the wireless device transmitted using a widebandcommunication mode, and wherein the at least one processor is configuredto: store status information indicating that the wireless device is in anarrowband communication mode, and in response to the uplink frame,update the status information to indicate that the wireless device is inthe wideband communication mode.
 3. The access point of claim 1, whereinthe indication comprises an uplink frame from the wireless devicetransmitted using a narrowband communication mode, and wherein the atleast one processor is configured to: store status informationindicating that the wireless device is in a wideband communication mode,and in response to the uplink frame, update the status information toindicate that the wireless device is in the narrowband communicationmode.
 4. A wireless device comprising: a wideband communicationinterface to communicate over a wideband channel, and a narrowbandcommunication interface to communicate over a narrowband channel; atleast one processor configured to: store a first rate set including aplurality of supported rates for communication over the widebandchannel, and a second rate set including a plurality of supported ratesfor communication over the narrowband channel, the first rate setincluding a supported rate not included in the second rate set, andsend, to an access point, an indication to change between use of thefirst rate set for communication through the wideband communicationinterface over the wideband channel, and use of the second rate set forcommunication through the narrowband communication interface over thenarrowband channel.
 5. The wireless device of claim 4, wherein theindication comprises a Traffic Specification (TSPEC) message or a BlockACK message.
 6. The wireless device of claim 4, wherein the at least oneprocessor is configured to send the indication responsive to a decisionby the wireless device to change between a wideband communication and anarrowband communication.
 7. The wireless device of claim 4, wherein theat least one processor is configured to receive the first rate set andthe second rate set from the access point.
 8. A method comprising:sending, by a wireless device to an access point, an indication to theaccess point that the wireless device is to transition between awideband communication and a narrowband communication; and receiving, bythe wireless device from the access point, a first rate set including aplurality of supported rates for communication over a wideband channel,and a second rate set including a plurality of supported rates forcommunication over a narrowband channel, the first rate set including asupported rate not included in the second rate set.
 9. The method ofclaim 8, comprising: communicating, through a wideband interface of thewireless device over the wideband channel, data with the access pointusing a rate of the first rate set during a time that the wirelessdevice is performing the wideband communication; and communicating,through a narrowband interface of the wireless device over thenarrowband channel, data with the access point using a rate of thesecond rate set during a time that the wireless device is performing thenarrowband communication.
 10. The method of claim 8, wherein sending theindication comprises sending a request to transition between thewideband communication and the narrowband communication, and wherein therequest comprises information relating to a narrowband communicationmode or a wideband communication mode to which the wireless device is totransition.
 11. The method of claim 10, further comprising: receiving,by the wireless device from the access point in response to the request,updated information relating to an operation of a network.
 12. Themethod of claim 10, further comprising: receiving, by the wirelessdevice from the access point, a response rejecting the request, theresponse containing a reason code for the rejecting.
 13. The method ofclaim 8, wherein the wireless device is currently operating in anarrowband communication mode, the method further comprising: sending anuplink frame in a wideband communication mode to indicate a transitionfrom the narrowband communication to the wideband communication.
 14. Themethod of claim 13, wherein the uplink frame includes informationsettable to: a first value indicating that the wireless device is tosend a predetermined number of uplink frames in the widebandcommunication mode followed by a transition back to the narrowbandcommunication mode, and a second value indicating that the wirelessdevice is to continue communicating in the wideband communication mode.15. The method of claim 8, wherein the wireless device is currentlyoperating in a wideband communication mode, the method furthercomprising: sending an uplink frame in a narrowband communication modeto indicate a transition from the wideband communication to thenarrowband communication.
 16. The method of claim 15, wherein the uplinkframe includes information settable to: a first value indicating thatthe wireless device is to send a predetermined number of uplink framesin the narrowband communication mode followed by a transition back tothe wideband communication mode, and a second value indicating that thewireless device is to continue communicating in the narrowbandcommunication mode.
 17. The method of claim 8, wherein the indicationcomprises an indication to change between the first and second ratesets.
 18. The method of claim 8, further comprising: scanning, by thewireless device, wideband channels to detect the access point;associating, by the wireless device, with the access point using aparticular wideband channel of the wideband channels; and afterassociating with the access point using the particular wideband channel,sending the indication that the wireless device is to transition fromthe wideband communication to the narrowband communication.
 19. Themethod of claim 18, wherein the scanning causes the wireless device todetect a plurality of access points, the method further comprising:selecting, by the wireless device, the access point from the pluralityof access points to associate with; and determining, by the wirelessdevice, which of the plurality of access points is capable of narrowbandoperation, wherein the selecting considers which of the plurality ofaccess points is capable of narrowband operation.
 20. The method ofclaim 19, wherein the selecting excludes an access point that does notsupport narrowband communication.
 21. The method of claim 8, furthercomprising: receiving, by the wireless device from the access point, afull rate set, wherein the first rate set is a subset of the full rateset, and the second rate set is a subset of the full rate set, the firstrate set including a given supported rate of the full rate set, thegiven supported rate not part of the second rate set.
 22. The method ofclaim 8, further comprising: exchanging, between the wireless device andthe access point, signaling to switch between the first rate set and thesecond rate set.